Explosive charge

ABSTRACT

A dual explosive charge comprising concentric layers of differing detonation velocity compositions for use against armoured targets, in underwater ordnance and for cratering. The charge consists of a core composed of a composition having a detonation velocity of less than 5,000 meters per second and an annulus having a detonation velocity above 5,000 meters per second.

United States Patent [1 1 Finnegan et al.

[111 3,742,859 [451 July 3,1973

EXPLOSIVE CHARGE Inventors: William G. Finnegan; Lohr A.

Burkardt; William B. McLean; William S. McEwan, all of China Lake; Edward W. Larocca, Placentia, all of Calif.

Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

Filed: Apr. 2, 1965 Appl. No.: 445,279

US. Cl 102/101, 102/24, 102/104,

149/8 Int. Cl. F421) l/00 Field of Search"; 102/98, 24, 101,

[56] References Cited UNITED STATES PATENTS 3,082,689 3/1963 Griffith et a1. 102/24 Primary Examiner-Robert F. Stahl Attorney-G. J. Rubens, R. Miller and V. C. Muller [5 7 ABSTRACT 6 Claims, N0 Drawings EXPLOSIVE CHARGE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to an improved explosive charge. More particularly, the invention relates to a composite or dual explosive charge comprising concentric layers of differing detonation velocity compositions.

The expanding techniques of modern weapons development lead to more and more specialized requirements for explosives. Dual or composite explosive charges have been developed utilizing mixtures of currently known high and low explosive compositions and other materials. The present invention is for an improved composite or dual explosive which is capable of producing greater follow-through damage than any other explosive of this type known today.

It is therefore an object of this invention to provide an explosive with enhanced penetrating power for use against armoured targets.

Another object is to provide an explosive which leaves water soluble explosive products making it useful for underwater ordnance.

Still another object is to provide an explosive useful in cratering.

Yet another object is to provide a composite or dual explosive charge having increased penetrating power for the amount of explosive.

A further object is to provide an explosive charge which gives high axial pressure and also provides a prolonged pressure peak.

Another object of this invention is to provide improved explosive charges which have enhanced reaction pressure or duration of detonation pressure.

These and other more specific objects of the invention will become apparent from the following detailed nation rate forms the outermost layer or annulus and surrounds the central core or innermost layer having a slower detonation rate. The charge may be enclosed in a suitable container which may be of any lightweight, self-sustaining, structurally weak material. Thin plastic, metal or cardboard is quite satisfactory.

The compositions found to be suitable'for this invention were chosen or formulated with care because the composition used for the core is critical to obtaining the penetrating damage for which the charge is intended. Conventional explosives with the proper low rate of detonation were not known. Compositions having a detonation velocity of less than 5,000 meters per second were found suitable for the core and those with a detonation velocity above 5,000 meters per second were found suitable for the surrounding annulus. 1n operation the charge is placed or propelled against the object to be damaged and detonated by firing the detonatable or sensitive outer layer. It functions to crater or partially cut a hole through the object and simultaneously initiates the detonation of the core composed of the low detonatable or insensitive composition. The core by virtue of its low velocity, completes detonation at a time later than that required for detonation of the surrounding layer of high detonation velocity material. Excess fuel in the detonation products of the core is forced in part through the hole formed in the target. This fuel reacts with air or water on the far side of the target to enhance damage in thisarea. If the pressure created by the high detonation velocity outer layer of the charge is not great enough to completely cut through the object, then the delayed response of the core explosion will tend to prolong the detonation pressure duration and will enhance the hole cutting ability of the high detonating velocity composition to a greater extent than an equivalent quantity of conventional high detonating velocity explosive.

The following examples will better illustrate this improved dual or composite explosive charge, but should not be construed as limiting it.

EXAMPLE I The core used in this charge consisted essentially of a stoichiometric mixture of three moles of magnesium powder and one mole of hexachloroethane. These ingredients were thoroughly blended and compressed at 40,000 pounds gauge pressure into pellets about 2 to 2% inches in diameter with a density of 1.83 grams per cubic centimeter. The outer layer or annulus which was pressed around the pellet was about 1% to 1 inch wide and consisted of a plastic demolition explosive known as composition C-3. This explosive has been standardized by the United States. It contains 78.0 i 2.0 percent cyclotrimethylenetrinitramine (RDX) and 22.0 i 2.0 percent explosive plasticizer which contains mononitrotoluene, dinitrotoluenes, trinitrotoluene and tetryl. Composition C-3 has a detonation rate of 7,625 meters per second. The explosive charge on test against a steel plate showed unusual damage caused by the unexpected pressure prolongation. This is due to the widely differing rates of detonation.

EXAMPLE n The low detonation composition comprising the core in this example consisted of a mixture of about 21.06 percent aluminum powder, 12.16 percent sulfur and 66.78 percent potassium perchlorate. The ingredients were blended and pressed into pellets. It has a detonation rate of about 1,500 meters per second. A layer of Composition B was cast around these pellets. Composition B was developed by the British during World War I and 11 and was standardized by the United States early in World War II. it contains about 55.2 percent cyclotrimethylenetrinitramine (RDX), about 40 percent trinitrotoluene (TNT), 1.2 percent polysoluctylene and 0.6 percent wax. Its detonation rate is 7,800 meters per second.

EXAMPLE Ill The core of this example consisted of about 60 percent by weight powdered aluminum and about 40 percent by weight ammonium nitrate. The mixture was pressed lightly into pellets and surrounded with a layer of Composition C-3, described in Example I hereinabove. Detonation of this charge demonstrated that the powdered metal over the stoichiometric amount permitted injection of metal vapor through the crater or hole. This phenomenon potentially enhances the damage which might be expected from a charge of this character by reaction of the metal fuel with oxygen containing media (air or water) on the far side of the target.

Other metals which may be used in place of aluminum include zinc, zirconium, boron and beryllium. Other oxidizers include potassium, sodium and lithium perchlorates and nitrates.

EXAMPLE IV The core of this example consisted of a Stoichiometric mixture of powdered aluminum and octachloropropane. The materials were blended and pressed into pellets which were covered with a layer of Composition C-3. Detonation of this charge gives the same type results as the charge described in Example 1.

EXAMPLE V EXAMPLE VI An explosive charge was prepared using Composition C-3 as the outer annulus and lithium and water as the central core. Because lithium reacts readily with water and must be stored in kerosene, gasoline or inert gases, the lithium used in the explosive charge was packaged in stick form in thin air-and-water-proof plastic cartridges which were then positioned in a thin plastic water-proof canister. Water was admitted to fill the spaces surrounding the cartridges and the canister was sealed. This formed the central core. Composition C-3 was pressed around the sides and top of the canister. The charge was then encased in a thin aluminum housing. n firing it demonstrated a powerful follow-through effect. The lithium could be contained in glass, copper, plastic or other suitable materials. Other reactive metals and alloys may be used.

Stoichiometry of reaction ingredients may be maintained to gain a maximum heat of explosion. The number of equivalents of powdered metal may be equal to the number of equivalents of chlorine or oxygen in the mixture. The percentage of powdered metal may be increasd over the stoichiometric amount, as shown in Example IIl, so as to permit injection of metal vapor through the crater or hole produced by detonation of the dual explosive charge.

The high detonation, sensitive composition comprising the outer annulus or layer may be any detonatable material of the brisance required for detonation of the insensitive or low detonation velocity core composition. Compositions having a detonation rate above 5,000 meters per second are preferred. Composition B has a detonation rate of 7,800 meters per second and Composition (3-3, which was often used because of its availability, has a detonation rate of 7,625 meters per second. Explosives such as dynamite, nitroglycerin, trinitrotoluene, pentaerythritol tetranitrate and cyclotrimethylenetrinitramine are all satisfactory. Many others will be apparent to those skilled in the art from this description.

The charges described herein were detonated by firing the sensitive composition or outer layer. This was done by an electrical detonator, but a booster charge or other suitable means. may be employed.

The composite explosive charges of this invention, cut much larger holes with more tearing and shattering than other types used heretofore. The recognition of an unexpected type damage caused by the followthrough explosive core makes this invention a valuable product.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An explosive charge comprising two concentric layers of explosive composition;

the inner layer consisting essentially of a Stoichiometric mixture of 1 mole magnesium and 3 moies hexachloroethane; and the outer layer consisting of 78.0 i 2.0 percent ylenetrinitramine and 22.0 :L- 2.0 percent explosive plasticizer;

said plasticizer consisting of mononitrotoluene, dinitrotoluene, trinitrotoluene and tetryl.

2. An explosive charge comprising a plurality of concentric layers of low detonation velocity compositions and high detonation velocity compositions;

the innermost layer being a low detonation velocity composition consisting essentially of magnesium and hexachloroethane; and

the outermost layer being a high detonation velocity composition consisting essentially of cyclotrimethylenetrinitramine, mononitrotoluene, dinitrotoluene, trinitrotoluene and tetryl.

3. An explosive charge comprising two concentric layers of explosive composition; the inner layer consisting essentially of of cyclotrimeth- Percent lngredients by weight Aluminum powder 21.06 Sulfur 12.16 Potassium perchlorate 66.78 and the outer layer consisting essentially of Percent Ingredients by weight Cyelotrimethylenetrinitramine' 55.2 Trinitrotoluene 40.0 Polyisoluctylene and 1.2 Wax 0.6.

Cyclotrimethylenetrinitramine Explosive plasticizer Percent by weight 60 40; and

Percent by weight 78 i 2 said plasticizer consisting of mononitrotoluene, dinithe outer layer consisting of 78.0 i 2.0 percent cyclo- "Qtoluelle, mmtrotoluelle and y trimethylenetrinitramine and 22.2 i 2.0 percent 6. An explosive charge comprising two concentric layers of explosive composition;

the inner layer consisting essentially of a stoichiometric mixture of aluminum and carbon tetrachloride; trotoluene, "initmtoluenea and 'l v and explosive plasticizer; said plasticizer consisting of mononitrotoluene, dini- 

2. An explosive charge comprising a plurality of concentric layers of low detonation velocity compositions and high detonation velocity compositions; the innermost layer being a low detonation velocity composition consisting essentially of magnesium and hexachloroethane; and the outermost layer being a high detonation velocity composition consisting essentially of cyclotrimethylenetrinitramine, mononitrotoluene, dinitrotoluene, trinitrotoluene and tetryl.
 3. An explosive charge comprising two concentric layers of explosive composition; the inner layer consisting essentially of Percent Ingredients by weight Aluminum powder 21.06 Sulfur 12.16 Potassium perchlorate 66.78;and the outer layer consisting essentially of Percent Ingredients by weight Cyclotrimethylenetrinitramine 55.2 Trinitrotoluene 40.0 Polyisoluctylene and 1.2 Wax 0.6.
 4. An explosive charge comprising two concentric layers of material, the inner layer consisting essentially of lithium and water the outer layer consisting essentially of cyclotrimethylenetrinitramine, mononitrotoluene, dinitrotoluene, trinitrotoluene and tetryl.
 5. An explosive charge comprising two concentric layers of explosive composition, the inner layer consisting essentially of Ingredients Percent by weight Aluminum 60 Ammonium nitrate 40; and the outer layer consisting of Ingredients Percent by weight Cyclotrimethylenetrinitramine 78 + or - 2 Explosive plasticizer 22 + or - 2 said plasticizer consisting of mononitrotoluene, dinitrotoluene, trinitrotoluene and tetryl.
 6. An explosive charge comprising two concentric layers of explosive composition; the inner layer consisting essentially of a stoichiometric mixture of aluminum and carbon tetrachloride; and the outer layer consisting of 78.0 + or - 2.0 percent cyclotrimethylenetrinitramine and 22.2 + or - 2.0 percent explosive plasticizer; said plasticizer consisting of mononitrotoluene, dinitrotoluene, trinitrotoluene, and tetryl. 